Turbine systems are continuously being modified to increase efficiency and decrease cost. One method for increasing the efficiency of a turbine system includes increasing the operating temperature of the turbine system. However, operating at high temperatures for extended periods often requires using newer materials capable of withstanding those conditions.
In addition to modifying component materials and coatings, one common method of increasing temperature capability of a turbine component includes the use of impingement cooling. Impingement cooling generally includes directing a cooling fluid through one or more apertures within an inner region of an article, the cooling fluid contacting (i.e., impinging upon) an inner surface of the article, which in turn cools the article. After impinging upon the inner surface of the article, a post-impingement fluid is typically directed away from the impinged surface, creating a cross flow within the inner region.
Usually, the cross flow includes higher velocity post-impingement fluid, known in the art as post-impingement wall jets, and lower velocity fluid between and adjacent the wall jets. Mixing of the higher velocity and lower velocity fluids usually happens in an inefficient manner, and causes relatively greater pressure losses in the cross flow, e.g., the cross flow has a relatively lower pressure head to provide additional function such as additional or sequential impingement cooling. A relatively lower pressure head can require additional cooling air, which is undesirable.